Bump cloudbees-folder-plugin to 6.1.0 to fix classic dashboard error (#1263)
Bump cloudbees-folder-plugin to 6.1.0 to fix classic dashboard error (#1263)

branch-api-plugin depends on cloudbees-folder-plugin 6.1.0.
jenkinsci/blueocean-plugin,jenkinsci/blueocean-plugin,kzantow/blueocean-plugin,jenkinsci/blueocean-plugin,jenkinsci/blueocean-plugin,alvarolobato/blueocean-plugin,alvarolobato/blueocean-plugin,jenkinsci/blueocean-plugin,kzantow/blueocean-plugin,alvarolobato/blueocean-plugin,kzantow/blueocean-plugin,kzantow/blueocean-plugin,alvarolobato/blueocean-plugin